%4.2f in the formatSpec input specifies that the first value in each line of output is a floating-point number with a field width of four digits, including two digits after the decimal point. %8.3f in the formatSpec input specifies that the second value in each line of output is a floating-point number with a field width of eight digits, including three digits after the decimal point. \n is a control character that starts a new line.
Next, I run a similar command, but with a 1 before >. Redirecting using the > signal is the same as using 1> to do so: I'm telling the shell to redirect the STDOUT to that file. If I omit the file descriptor, STDOUT is used by default. I can prove this by running the sdiff command to show the output of both commands side by side:
In all the previous examples, whenever I redirected some output, I used a single >, which means "send something to this file, and start the file from scratch." As a result, if the destination file exists, it is overwritten.
The above example lists my processes, filters any that contain the string chrome, ignores the line about my grep command, and counts the resulting lines. If I want to send the output to a file, I add > and a file name to the end of the chain.
Those were some examples of redirecting STDOUT and STDERR. Putting all this together, you realize how powerful redirection can be. By chaining individual commands, manipulating their output, and using the result as the input for the next command, you can perform tasks that otherwise could require you to develop a script or program. You could also incorporate the technique into other scripts, using everything as building blocks.
I am trying to get .txt output files from Python, but I have serious problems with overwriting my .txt file every time I run the program (the output .txt file always has the same name). Now I have this commands:
I am really interested in knowing how to automatically rename this output .txt file (now called 'outputHorizontal.txt'), in order to have data from every time I run the program. Is there any way to make the name change according to the input that the user has to enter in the program to run it? For example, the latitude (as 'lat) is a input of the program, and would be nice to make the txt file name could be changed automatically according to 'lat' (every time 'lat' changes, the txt file names also changes).
Be sure to import sys module. print whatever you want to write and want to save. In the sys module, we have stdout, which takes the output and stores it. Then close the sys.stdout . This will save the output.
You might expect that typing dir t97\* would return the file t97.txt. However, typing dir t97\* returns both files, because the asterisk wildcard matches the file t.txt2 to t97.txt by using its short name map T97B41.TXT. Similarly, typing del t97\* would delete both files.
You can use the question mark (?) as a substitute for a single character in a name. For example, typing dir read???.txt lists any files in the current directory with the .txt extension that begin with read and are followed by up to three characters. This includes Read.txt, Read1.txt, Read12.txt, Read123.txt, and Readme1.txt, but not Readme12.txt.
If you use the redirection symbol (>) to send this command's output to a file, or if you use a pipe () to send this command's output to another command, you must use /a:-d and /b to only list the file names. You can use filename with /b and /s to specify that this command is to search the current directory and its subdirectories for all file names that match filename. This command lists only the drive letter, directory name, file name, and file name extension (one path per line), for each file name it finds. Before you use a pipe to send this command's output to another command, you should set the TEMP environment variable in your Autoexec.nt file.
The output lists the root directory, the subdirectories, and the files in the root directory, including extensions. This command also lists the subdirectory names and the file names in each subdirectory in the tree.
You can also redirect output of the dir command to a file by replacing prn with a file name. You can also type a path. For example, to direct dir output to the file dir.doc in the Records directory, type:
The array values 1-100 are sent down the pipeline to the ForEach-Object cmdlet. ForEach-Objectuses a script block with the Add-Content cmdlet to create the LineNumbers.txt file. The variable$_ represents the array values as each object is sent down the pipeline. The Get-Content cmdletuses the Path parameter to specify the LineNumbers.txt file and displays the content in thePowerShell console.
This command gets the first five lines of a file. The TotalCount parameter is used to gets thefirst five lines of content. This example uses the LineNumbers.txt file that was created inExample 1.
This command gets a specific number of lines from a file and then displays only the last line ofthat content. The TotalCount parameter gets the first 25 lines of content. This example uses theLineNumbers.txt file that was created in Example 1.
This example describes how to use the Stream parameter to get the content of an alternate datastream for files stored on a Windows NTFS volume. In this example, the Set-Content cmdlet is usedto create sample content in a file named Stream.txt.
The commands in this example get the contents of a file as one string, instead of an array ofstrings. By default, without the Raw dynamic parameter, content is returned as an array ofnewline-delimited strings. This example uses the LineNumbers.txt file that was created in Example1.
A warning occurs when you use the AsByteStream parameter with the Encoding parameter. TheAsByteStream parameter ignores any encoding and the output is returned as a stream of bytes.
Specifies, as a string array, an item or items that this cmdlet includes in the operation. The valueof this parameter qualifies the Path parameter. Enter a path element or pattern, such as"*.txt". Wildcard characters are permitted. The Include parameter is effective only when thecommand includes the contents of an item, such as C:\Windows\*, where the wildcard characterspecifies the contents of the C:\Windows directory.
Keeps the file open after all existing lines have been output. While waiting, Get-Content checksthe file once each second and outputs new lines if present. You can interrupt Wait by pressingCTRL+C. Waiting also ends if the file gets deleted, in which case a non-terminating error isreported.
This is because the standard output for the command was redirected to a file called myoutput.txt. The file now exists in the same directory where you ran the command. The standard error output still displays as it normally does.
As you can see, any error messages from the command are output to the error file. Just as with the standard output, you can use >> instead to append the error to errors from previously run commands.
You can perform any of the same output commands above from inside a BAT file and the output from that line will go to the output file you specify. This is a useful way to see whether any commands within a BAT file had any errors when they tried to run.
Here, since redirections are processed in a left-to-right manner, the standard error stream would first be redirected to wherever the standard output stream goes (possibly to the console), and then the standard output stream would be redirected to a file. The standard error stream would not be redirected to that file.
Here, you redirect standard error to the same place as the standard output stream. This means that both streams will be piped to the tee utility as a single intermingled output stream, and that this standard output data will be saved to the given file by tee. The data would additionally be reproduced by tee in the console (this is what tee does, it duplicates data streams).
Note that you would not be able to reproduce the effect of the second pipeline with just > (as in utility >output.log 2>&1, which would save both standard output and error in the file by first redirecting standard output to the output.log file and then redirecting standard error to where standard output is now going). You would need to use tee to get the data in the console as well as in the output file.
In the first pipeline, more_stuff would get what's originally the standard error stream from utility as its standard input data, while in the second pipeline, since it's only the resulting standard output stream that is ever sent across a pipe, the more_stuff part of the pipeline would get nothing to read on its standard input.
2>&1 >output.log means first start sending all file handle 2 stuff (standard error) to file handle 1 (standard output) then send that to the file output.log. In other words, send standard error and standard output to the log file.
2>&1 tee output.log is the same with the 2>&1 bit, it combines standard output and standard error on to the standard output stream. It then pipes that through the tee program which will send its standard input to its standard output (like cat) and also to the file. So it combines the two streams (error and output), then outputs that to the terminal and the file.
The bottom line is that the first sends stderr/stdout to the file, while the second sends it to both the file and standard output (which is probably the terminal unless you're inside another construct which has redirected standard output).
The reason for 2>&1 tee is to be able to capture both stdout and stderr to a log file and to see it on the screen at the same time. This could be done as >output.txt 2>&1 & tail -f as well, but you wouldn't know when the backgrounded command terminated - is the program terminated or is it running with no output. The 2>&1 tee was a common idiom for programmers. 041b061a72